Callisto was a nymph that accompanied Artemis in her hunt. Zeus, however, had taken a certain interest in Callisto. Knowing that she would never admit Zeus anywhere near herself because of a vow of chastity, he transformed himself into Artemis in order to deceive her. Callisto was indeed deceived by Zeus’ appearance as Artemis, and seizing the opportunity, Zeus raped her. Callisto became pregnant with Zeus’ child, and when Artemis found out she became enraged and ostracized Callisto from her fold. Hera, Zeus’ wife, was extremely jealous of Callisto since she caused her husband’s infidelity. Hera transformed Callisto into a bear, and the expected son was sent away to be raised by Hermes’ mother, Maia. Callisto’s son was named Arcas, which means “bear,” and when he grew up he became a hunter. When Arcas was out hunting, he confronted Callisto who was transformed into a bear. Although Callisto recognized her son, he could not recognize his mother, and pierced the bear with his spear. Zeus sympathized with Callisto, and transformed her into the constellation Ursa Major, meaning “great bear.” Zeus also transformed Arcas into Ursa Minor, “little bear,” and placed him in the skies next to his mother.